“THEY’RE NOT REPUBLICANS. THEY’RE WHIGS.”

Those who style themselves “true conservatives” aren’t the brightest bulbs in the chandelier, as their constant misuse of their favorite epithet indicates.

“RINO” is an acronym, for “Republicans In Name Only.” Those who use it think only a “true conservative” can (or should be) a Republican.

Most Republicans are conservative. This should give the GOP an electoral advantage. In Gallup’s annual poll in January, 38 percent of Americans described themselves as “conservative;” 34 percent said they were “moderate;” only 28 percent were “liberal.”

Among Republicans, 70 percent said they’re conservative; 24 percent said they’re moderate.

To prevail in a two- party system where elections are decided by majority vote, Republicans must get lots of votes from those whom “true conservatives” deride as RINOs.

Alas, electoral math is as baffling for “true conservatives” as budget math is for Democrats.

The voting index maintained by the American Conservative Union indicates Republicans in Congress are a scoche more conservative than the voters who elected them.

But rank-and-file Republicans despise Senate Majority Leader Mitch McConnell, R-KY, and House Speaker John Boehner, R-OH, for a very good reason: They’re not Republicans. They’re Whigs.

The Whigs were the chief rivals of the Democrats from 1834 to 1852. The Whigs disappeared because they tried to duck the great moral issue of their time.

The Whigs were replaced by the Republicans, who embraced it. Not before or since has a political party had a platform more succinct, clear and compelling than did the Republicans in 1856: “Free Speech, Free Press, Free Soil, Free Men, Fremont and Victory.”

“Lincoln and Liberty, Too” — the Republican campaign song in 1860 — called upon “all true friends of the nation to aid in the slaves’ liberation.”

The party of slavery and segregation has done nothing to prevent, much to facilitate, the murder of thousands of Americans by violent felons among illegal immigrants. Passage of “Kate Steinle’s Law” to cut off federal funds for so-called “sanctuary cities,” and to make the Democrats who run them liable for wrongful death suits, is one of two great moral imperatives for 2015.

The other is to end federal subsidies for Planned Parenthood’s abortion mills. The 9 gruesome, macabre, heartbreaking videos released so far by the Center for Medical Progress make plain the wine-swilling Mengeles who run PP have committed multiple felonies.

Since these are budget issues, the proper place to address them is in the budget for the new fiscal year that begins Oct. 1. But Sen. McConnell already has said he won’t, so fearful is he that Republicans will be blamed if the government is “shut down” over a budget impasse.

You defeat evil by fighting it, not by surrendering pre-emptively to it. Sen. McConnell, Rep. Boehner et al aren’t evil. But their reluctance to resist evil makes them pathetic excuses for human beings. In the words of the greatest Whig, Henry Clay, they aren’t worth the powder and shot to kill them.

Fighting risks defeat. Most in the “mainstream” media will grossly exaggerate the effect of a government “shutdown” and blame Republicans for it. (The chief consequence of a budget impasse is that the federal government may not borrow money. It can spend only what it receives in tax revenues. This eventually becomes a problem. But it doesn’t emerge for months.)

But fighting is the only way to win.

“For the media to play up this shutdown fight…they first have to explain what this controversy is all about,” said Ben Domenech of the Heartland Institute. “That is the last thing they want to do.”

If Republicans seize the opportunity to detail the crimes committed by illegal immigrant felons, play the most gruesome parts of the Planned Parenthood videos, and quote PP founder Margaret Sanger on her goal of exterminating blacks, millions of Americans will be shocked and outraged, wonder why they hadn’t been told about this before.

After a month or so of this, I doubt it’ll be Republicans who throw in the towel.

Jack Kelly is a former Marine and Green Beret, and was the Deputy Assistant Secretary of the Air Force during the Reagan Administration. He is the national security writer for the Pittsburgh Post-Gazette